Bio171-KEY E2 W10 - BIO 171 Exam 2 Winter 2010 Multiple...

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1 BIO 171 Exam 2 Winter 2010 Multiple Choice Answer Key FORM 1 D,C,C,E,D,B,A,E,D,C,D,E,A,D,C,B,A,E,B,A,A,C,B,A,B,B,A,E,D,D FORM 2 B,A,A,C,B,D,C,C,E,D,B,A,E,D,C,D,E,A,D,C,A,E,A,B,B,A,E,D,D,B FORM 3 D,E,A,D,C,B,A,A,C,B,D,C,C,E,D,B,A,E,D,C,A,E,A,B,B,A,E,D,D,B Short answer key starts on next page
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2 Biology 171 Exam 2 Winter 2010 Answer KEY SHORT ANSWER QUESTIONS: You MUST answer ONLY 4 of these questions. Draw an X through the Q you are choosing not to answer. SA1 . In temperate deciduous forests in the US, chickadees (small birds) eat a large variety of invertebrates during the nesting season. The chickadee diet includes caterpillars that feed on oak trees AND spiders that feed on the oak-feeding caterpillars (10 pts total, A-C) A) Draw a diagram that represents the feeding relationships among oaks, caterpillars, spiders and birds. Use “minus” signs to clearly illustrate the direct negative effects that each of the predators has on its prey (3). What name do we give to the feeding strategy exhibited by the birds in this system? (1) (Give 1 point each for (a) having all the species on the figure, (b) having all the signs as negative, and (c) having the arrows pointing in the same direction and in the right place. Omnivory (1) B) Without additional information, is it possible to predict the overall effect of chickadees on caterpillar populations? (1). Explain your answer carefully (2). No (1) Birds have a direct negative effect on caterpillars but an indirect positive effect on caterpillars (1). We don’t know the net effect of birds on caterpillars without knowing the relative strengths of the direct and indirect effect (1). C) Imagine that a new parasite arrives in 2010 and dramatically reduces the chickadee population. You now observe much higher caterpillar populations than before, and the oaks have had all of their leaves consumed by the caterpillars. What do we call an interaction that extends from the top predator all the way down to the primary producer? (1). Using the extra information that we gained from the arrival of the parasite, what can we now conclude about the relative importance of direct and indirect effects of chickadees on caterpillars? Explain your answer carefully (2). Trophic Cascade (1) The direct effect of birds on caterpillars must be stronger than the indirect effect (1). When birds are removed, caterpillars increase – they would decrease if the indirect positive effect was stronger (1).
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3 SA2 . Like all scientists, Darwin “stood on the shoulders of giants” as he developed his theory of
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This note was uploaded on 09/13/2010 for the course BIO 171 taught by Professor Josephinekurdziel during the Spring '08 term at University of Michigan.

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Bio171-KEY E2 W10 - BIO 171 Exam 2 Winter 2010 Multiple...

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